I'm trying to make a mould off of an interior trim piece, since it had texture on it, I went ahead and used filler primer to smooth it out and wet sanded (the whole nine yards). Now I wanna make a mould off if it.

I know that the fiber glass resin/polyester resin will eat up the primer. is there any coating that I could spray on it, and use fiberglass to make a mould off of? or is there any other ways that you guyz might know of?

thanks.

mold :-)

I'm also in the process of trying to make a mold.

You first need to make sure you have a smooth non-pourus surface. Best way to make sure of that is to use a gloss coat, any color will do but black is great for showing imperfections.

Next you need to wax the piece you want to make a mold of. They have special mold release wax out there, but 100% pure carnuba wax may work.

Next you want to spray PVA (polyvinyl alcohol) over your waxed piece. It's another type of mold release <- This is where I'm at right now.

Next you want to put a gel coat over the piece. They sell special gel coats, but plain polyester resin should work.

Allow the gel coat to cure partially and then apply resin and mat to give the mold strength.

And if the mold didn't stick to your part you should be able to seperat them.

To make a piece from the mold follow the same steps on the mold.

Don't use polyester resin with gel coat, it won't stick well, and eventually it will pull apart. I posted a step by step a while back, but here's a quick overview. After you get the surface smooth use release wax and PVA as stated above (DO NOT use carnuba wax with PVA). After you do 2-3 coats of wax and spray a few laters of PVA you can brush or spray on gel coat. Tooling gel coat is the best for molds because it's smoother and super gloss, it's made for a better release and finish. If you don't want to spend the money on tooling gel coat, regular white gel coat will work, but not as good results. After the gel coat gets tacky you can start layering the fiberglass. You can use either fiberglass mat or cloth, but i prefer mat. The resin you want to use is epoxy resin, the same as you would carbn fiber, it's stonger and bonds to gel coat better. Brush on a layer of resin, then a layer of mat, layer of resin, layer of mat etc.. I use 5-6 layers if not more for molds because i re-use them so i want them to be storng. If you're doing a one time mold, then it can be thinner. Hope you understood this, i was typing in a hurry. Good luck.